Jackie Ashley (The return of left-right politics in the UK will make 2012 fascinating, 2 January) is wrong to argue that David Cameron may not want Boris Johnson to win the London election. The Tory party has no interest in losing the capital two years into this government's term. It will show that no Tory anywhere – not even Johnson – is immune. Cameron told Tory MPs only last month that Johnson's election was his No 1 priority. Johnson and Cameron stage their disagreements to help them both. The Guardian reported last year (14 June) that their "rows" were conducted within "Queensberry rules". It has been widely reported that Cameron, Osborne and Johnson text each other on a "near daily" basis as part of an "agreed strategy" for the election. In one meeting between the PM and the mayor, the PM is reported to have told Johnson last year that "not only do I want you to win next year because we are friends, but I recognise there is no way you losing would be seen as anything but a disaster for me". They are so worried by Ken Livingstone's plan for a fares cut that Osborne found £130m to make this year's above-inflation rise appear less painful – to no avail. We should not pretend Cameron wants Johnson to lose. He doesn't.Paul Kenny General secretary, GMB,Billy HayesGeneral secretary, CWU, Tom Watson MP,Seema Malhotra MP,Len Duvall Assembly member (AM) Val Shawcross AM,Lord Toby Harris

• This letter was amended on 2 February 2012. The original referred to "Queensbury rules". This has been corrected.